A conventional range finder has been described, for example, in Patent Literature 1. In the present range image sensor, all four sides of a photo sensitive region into which light is made incident are surrounded by four transfer gate electrodes, transfer voltages different in phase are applied to these transfer gate electrodes, and charges generated at a photo sensitive region will flow sequentially into four charge accumulating regions located outside the transfer gate electrodes. In the range image sensor, on the basis of charge quantities distributed into the accumulating regions, a distance to an object is calculated.